The principles of natural selection in the evolution of populations: random mutation can produce new alleles; advantageous alleles in certain environments lead to increased reproductive success; the advantageous allele is inherited by the next generation; over many generations the new allele increases in frequency
Natural selection is the process where organisms with a useful inherited variant survive and reproduce more. Over many generations, that variant becomes more common in the population.
Real World
MRSA (methicillin-resistant Staphylococcus aureus) evolved through natural selection: random mutations gave rare bacteria resistance to antibiotics, those bacteria survived and reproduced in hospitals, and resistance alleles spread through the population within decades.
Exam Focus
Use the word 'allele' throughout, and always end with allele frequency increasing over generations — missing this final step is the most common mark loss.
Evaluation Scaffold
A four-step framework for high-quality evaluation. Use this for 'assess', 'evaluate', and 'to what extent' questions.
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